HomeMy WebLinkAboutCDP 2019-0032; TELESCOPE HOUSE: BUILD NEW SFR; REVIEW OF GEOTECHNICAL REPORT; 2020-08-14City of Carlsbad
1635 Faraday Avenue
Carlsbad, California 92008
Attention: Ms. Kyrenne Chua
Subject: Review of Geotechnical Report
Project: Love Residence
4615 Telescope Avenue
Carlsbad, California
City Project ID: CDP2019-0032
City GR No.: 2020-0019
August 14, 2020
Project No.: 226816-00101.73
RECKffVE
AUG 252020
LAND DEVELOPMENT
ENGI NEERING
References: 1) "Geotechnical Investigation, Proposed Single-Family Residence 4615 Telescope
Avenue, Carlsbad, California," prepared by Hetherington Engineering, Inc., Project No.
8787.1, dated March 11, 2019.
"Grading Plans for: Love Residence, APN: 207-385-20 (4615 Telescope Avenue)",
Sheet 2 of 4 sheets, prepared by Sampo Engineering, Inc., Job Number 19-110, dated
May 28, 2020.
"Technical Guidelines for Geotechnical Reports", issued by the City of Carlsbad, dated
January 1993.
"CGS Note 41, Guidelines for Reviewing Geologic Reports", prepared by the State of
California, Department of Conservation, California Geological Survey, dated 2017.
Dear Ms. Chua:
As requested, NV5, West Inc. (NV5) has conducted a geotechnical review of the above-referenced
geotechnical report and grading plan for the proposed project located in Carlsbad, California. The purpose
of the review was to provide an opinion on whether the geotechnical aspects of the project have been
identified and appropriately addressed in the project geotechnical report. NV5's geotechnical review is
based on geotechnical information presented in the referenced geotechnical report and experience with
the geotechnical conditions in the general site area. NV5 has not performed an independent geotechnical
investigation at the project site,and therefore does not offer or imply any guarantee or warranty as to
future site performance. The opinions presented below are limited. Other consultants could arrive at
different conclusions. This report presents a summary of the review.
Review Summary
Based on our review, the referenced geotechnical report for the proposed project has generally
identified and addressed the significant geotechnical factors affecting the site development as
currently proposed, and the report is approved. Note that acceptance or approval of the report does
not guarantee or constitute approval for grading or building permits. Although the report is approved
the following comments are provided for consideration:
5092 AvuE OF SCIENCE, SLIfTE 200 SAN DIEGO. CA 92 128 vv N15.COFI I OFFICE 858.850500 F 858.385000
Cc rc:;crO.tQijar -
F-
Review of Geotechnical Report
City Project ID: CDP2019-0032
Love Residence
4615 Telescope Avenue
Carlsbad, California
Project No.: 226816-00101.73
On page 8 in Section 5 titled, "Foundations and Slab Recommendations", the referenced
geotechnical report (reference 1) recommends that slab-on-grade floors should be underlain
by a 10-mil polyethylene moisture vapor retarder, and that 2 inches of sand be placed below
the vapor retarder and 2 inches of sand should be placed above the vapor retarder.
Current ACI standards no longer recommend the use of sand over a moisture barrier, but
recommend that the concrete be placed directly on the moisture barrier, and to compensate
a lower water cement ratio and improved curing methods are suggested. It is also noted that
the use of thicker moisture barrier products such as Stego WraplM, Moistop PIusTM (not
excluding other products) have been shown to provide superior performance related to
reduced moisture infiltration and increased tear resistance during slab construction.
It is recommended that the project geotechnical consultant review and approve the grading,
shoring and building foundation plans prior to construction.
NV5 appreciates the opportunity to be of service to you on this project. If you have any questions
regarding this report, please do not hesitate to contact our office.
Respectfully submitted,
NV5 West, Inc.
Gene Custenborder, CEG 1319 Carl Henderson, PhD, GE 2886
Senior Engineering Geologist CDO / SoCal CQA Group Director
GC/CH
Attachment: Geotechnical Review Checklis
a ESSI
SCOk
Distribution: (1) Addressee, via email
QtMTY TLCtE GN M . E otjt
I GEOTECHNICAL REPORT REVIEW CHECKLIST
Plan Check Number: CDP20190032/GR20200019
Location I Address: 4615 Telescope Avenue
City Plan Checker: Date: August 14, 2020
GEOTECHNICAL REPORT - GENERAL
OK NOT
MET N/A
Signed by RCEIGE P1 LI LI
Signed by CEG (Required for Hillside Area) Z LI LI
Project Address LI El
Location Index Map with reference north, scale, etc. LI LI
Site Description (topography, vegetation, existing structures/improvements, drainage) Z LI LI
Description of Proposed Development (grading, structures/improvements, drainage, use, foundation
type, estimated structural loads)
ie LI LI
GEOTECHNICAL REPORT - FIELD INVESTIGATION
OK NOT
MET N/A
Site Specific Subsurface Investigation JA LI 0
Description of Investigative and Sampling Methods LI LI
Boring/Test Pit Logs (Soil/Bedrock descriptions with depth, type and depth indicated for sampling,
real assumed _or_ _elevation _indicated, _groundwater _conditions)JZ LI LI
Sampling performed to anticipated depth of foundations and/or deepest excavation LI LI
Boring/Test Pits located on Geotechnical Map/Plot Plan LI LI
Revised 5/10/2018 1 of 7
GEOTECHNICAL REPORT - LAB TESTING
OK NOT
MET N/A
Description of lab test performed with referenced test method (ASTM, EPA, etc) / El 0
Soil Strength (Shear) El El
Expansion El El
Sulfate ' El 0
Gradation 0 El
Classification of soil in accordance with ASTM D 2487 (when using California Building Code values
for lateral load)
El El
Moisture/Density El El
Consolidation El El
Atterberg Limits El El
Maximum Dry Density/Optimum Moisture Content El 0
GEOTECHNICAL REPORT - EARTH MATERIALS
OK NOT
MET N/A
Description and designation of geologic units (surficial soils and bedrock, including depth, thickness) z El El
Geologic structure (bedding, fracturing, faulting of bedrock material) 14 El El
Description of regional geologic conditions (including reported regional trends of bedding and
faulting) El El
GEOTECHNICAL REPORT - SEISMICITY
OK NOT
MET N/A
General description of regional and local faulting Ill El El
Site Class El El
Mapped Spectral Acceleration Parameters (Se, Si) Li El El
Site Coefficients (Fa, F) El El
Design Spectral Acceleration Parameters (Sos, SD1) ie 0 0
Geotechnical Report Checklist
Revised 5/10/2018 Page 2 of 7
Seismic Design Category LI LI
GEOTECHNICAL REPORT - GEOLOGIC HAZARDS
OK NOT
MET N/A
Landslide LI LI
Expansive Soils LI LI
Surficial Slope Instability LI LI I
Slope Creep C] LI /
Groundwater 0 LI
Total and Differential Settlement LI LI
Sulfate LI LI
Liquefaction LI LI
Affect of liquefiable soils on utilities and lifeline services outside of structural mitigation LI LI
Seismic Induced Landsliding LI LI I
Tsunami Potential I LI LI
GEOTECHNICAL REPORT - ILLUSTRATIONS
OK NOT
MET N/A
Geotechnical Map I Plot Plan LI LI
Existing topography / improvements LI LI
Proposed topography I improvements LI LI
Location of subsurface exploration (borings, test pits, etc.) E/ LI LI
Geologic Contacts LI LI
Geologic Structure LI LI
Location of fill key I buttress LI LI 49
Geologic Cross-Section / LI LI
Existing topography I improvements JZ LI LI
Geotechnical Report Checklist
Revised 5/10/2018 Page 3 of 7
Proposed topography / improvements El El
Location of subsurface exploration (borings, test pits, etc.) El El
Geologic Contacts El El
Geologic Structure El El
Slope setbacks El El
Temporary cuts / shoring El El
Fill Key / buttress El El I
Slope benching El El
GEOTECHNICAL REPORT - CONCLUSIONS I RECOMMENDATIONS
OK NOT
MET N/A
Statement as to feasibility of project El El
Statement as to impact on adjacent properties / El El
Statement of the condition of slopes with respect to stability W1 El El
Slope stability analysis provided to support conclusion/recommendations El El
Statement regarding liquefaction potential , El El
Liquefaction analysis provided to support conclusion/recommedations El El f
Grading Recommendations El El
Remedial grading El El
Compaction standards 4C El El
Groundwater Mitigation El El
Temporary excavation (backcuts, slopes) with time limit recommendations El El
Shoring El El
Benching El El I
Keys / buttresses El El
Canyon/Key Subdrains El El d]
Foundation Recommendations Z El El
Geotechnical Report Checklist
Revised 5/10/2018 Page 4 of 7
Expansive soil mitigation (CBC 1805) Z LI LI
Description of approved embedment material (i.e. compacted fill, terrace deposits, etc) Vt LI LI
Minimum depth of embedment (into approved material) for foundations I LI LI
Minimum width of footings LI LI
Minimum diameter of caissons LI LI
Bearing capacity (end bearing for caissons) LI LI
Coefficient of friction (caisson skin friction) ie LI LI
Lateral bearing [' LI LI
Down drag forces (liquefiable soils,) LI LI [1'
Lateral Spread forces (liquefiable soils) LI LI
Foundation slope/trench setback P1 0 LI
Minimum reinforcement requirements LI LI
Minimum slab thickness and reinforcement , LI LI
Slab underlayment LI LI
Soluable Sulfate exposure mitigation (typically cement type) LI 0
Conventional Retaining Wall Recommendations LI LI
Active pressures (level, sloping) LI LI
Retaining wall backdrain or recommendation of additional hydrostatic pressure LI LI
Backfill 4e LI LI
Surcharges I LI LI
MSE Wall Recommendations (facing material, grid, backfill, stability analysis) LI LI /1
Flatwork / Hardscape recommendations including driveways (subgrade preparation, minimum slab
thickness, reinforcement and joint spacing)
LI LI
Roadway Pavement recommendations (section design, subgrade preparation) LI LI
Swimming Pool recommendations 0 LI
GEOTECHNICAL REPORT - OBSERVATION/TESTING DURING CONSTRUCTION
Geotechnical Report Checklist
Revised 5/10/2018 Page 5 of 7
OK NOT
MET N/A
Footing Excavations El El !
Subdrains El El
Caisson / Drilled Pier excavations (CBC Table 1704.9) LII El I
Pool Excavations El El ,
Benching El El
Keyways El El
Temporary excavations El El
Geologic mapping of bedrock excavations El El
Retaining wall backfill El El
Utility trench backfill El El
Engineered fill El El
Hardscape subgrade (driveways, patios, walkways, etc.) El El
Import soils El El
GEOTECHNICAL REPORT - REFERENCES
OK NOT
MET N/A
Current / City adopted Building Code El El
Grading Code El El
Geotechnical reports I publications I geologic maps El El
Ariel photographs El El
Websites El El
GEOTECHNICAL REPORT - COASTAL BLUFF
OK NOT
MET N/A
Top of bluff designation (presented on geologic map and cross-sections) U El
Ceotechnical Report Checklist
Revised 5/10/2018 Page 6 of 7
Anal photograph of site showing top of bluff U LI
Bluff retreat rate and total estimated retreat for a 50 year period U U /
Codified Bluff top setback (presented on geologic map and cross-sections) U U
Slope stability analysis U El
References for bluff retreat rate LI U
Slope Stability Setback presented on geologic map (surface expression of 1.5 FS) U U
Total Setback presented on geologic map (greater of A: Slope Stability Setback + 50 yr bluff retreat
or B: 10-feet buffer + 50 yr bluff retreat) U U
Explanation and justification of 40-feet setback deviation U U
Geotechnical Report Checklist
Revised 5/10/2018 Page 7 of 7
Ismael Quero
From: pbogseth@hetheringtonengineering.com
Sent: Friday, August 21, 2020 3:03 PM
To: Ismael Quero
Cc: Zarel Lomeli; Vince Sampo; elitehomeconstruction@yahoo.com
Subject: RE: Love Residence
Follow Up Flag: Follow up
Flag Status: Flagged
Ismael,
We agree with the first item. A 15 mil vapor barrier is a better product and suggested.
Based on the plan and our prior work, it appears shoring is not needed. There is room for the temporary excavations.
Paul Oogseth PG, CEG, CHG
Principal Engineering Geologist
Hetherington Engineering, Inc.
Carlsbad, California 760-931-1917
Laguna Beach, California 949-715-5440